Data sources

Studies were identified by searching Medline, the Cochrane Library, and EMBASE/Excerpta Medica from their inception to December
1999 with the terms asthma, herb with various endings, Ayurvedic, and traditional Chinese medicine as well as names of individual
herbs. Bibliographies and personal reprint collections were scanned, and experts were contacted.

Study selection

Randomised controlled trials were included if they studied patients with asthma preferably defined using American Thoracic
Society criteria, and if they reported outcomes of lung function tests, FEV1, or airway resistance.

Traditional Indian herbal (Ayurvedic) medicine.

Quality scores for these trials ranged from 1 to 4. All patients in the 8 trials had bronchial asthma. Boswellia serrata gum was more effective than placebo for improving FEV1 (80 patients). Solanum xanthocarpum or S trilobatum showed improvement from baseline FEV1, but this was not as effective as standard drugs (salbutamol or deriphylline) (60 patients). Tylophora indica was studied in 5 trials (30-195 patients) of which 3 showed an improvement in FEV1 or symptoms; 1 trial showed 1 week improvements in self reported symptoms that were not sustained at 12 weeks. Picrorrhiza kurroa showed no improvement in FEV1 or symptoms over placebo (72 patients).

Conclusion

Although a number of randomised controlled trials have shown that herbal preparations improve FEV1, symptoms, or both in patients with asthma, their value remains uncertain because study quality is generally poor.

Commentary

Lecturer and Nurse Practitioner Department of Health Studies University of York York, UK

This systematic review by Huntley and Ernst makes an important contribution in an area of growing interest. The authors note
that 60% of people with moderate asthma and 70% with severe asthma have used complementary and alternative medicine.

Although the authors included studies of any language, the databases that were searched include mainly studies of Western
medicines published in English and so may not be the best source of evaluations of herbal medicines. The studies reviewed
had poor methodological quality; 14 of the 17 studies scored ≤3 on the Jadad scale, and only half were double blinded. Most
of the studies did not evaluate products of standardised quality.

Asthma is of considerable clinical interest, affecting about 10% of the population of England and Wales.1 This review is of relevance to the large number of nurses who manage patients with asthma in primary care and respiratory
specialist nurses in the acute sector. The popularity of complementary treatment may arise from concerns by patients and parents
about the side effects of conventional inhaled or oral steroid medication, and possibly the cost of traditional treatments.

The review indicates that herbal medicines may have an anti-inflammatory effect; however, Blanc et al raise the concern that patients' use of alternative treatments may delay appropriate use of conventional medicines and thus
increase the risk for life threatening episodes.2 Huntley and Ernst also emphasise that many herbal remedies have side effects (eg, headaches, nausea, bleeding, and seizures)
and some interact with conventional medicines such as anticoagulants. Caution is required when using them therefore and more,
better quality research about efficacy and safety is needed before nurses can confidently recommend them to patients.